Yes, an astroid named Luna crashed into the earth while it was still forming,thus forming the moon
Without the Moon, Earth would often be a much darker place at night.
The tides would still occur, but would be driven only by the Sun. So, they would be considerably less dramatic and powerful than what we have.
Tidal differential and intertidal zones would be much smaller. All tides would be much weaker, but in terms of lakes and streams the differences would, of course be slight.
There would be some surprises, but ocean waves, earthquake driven tsunami, and the like would continue to occur. However, earthquakes and volcanism would be suppressed to some extent. This lessening of frictional forces might have, at least a slight cooling effect on Earth's internal temperature.
Some biologists think that the most important step in evolution (life moving to land) may not have occurred as soon, or perhaps at all. So, without the tides, evolution might have employed a very different path, with correspondingly different results in a very different time frame.
Since the moon formed, it has been slowing Earth's spin. The orbiting of Earth's moon is the most influential force affecting the length of Earth's day. As the moon moves farther away, the rate of increase of Earth's day will decrease over time. Earth's day will continue to increase as long as the moon continues to orbit Earth, but its effect will lessen as its orbital distance from Earth increases.
Whatever stabilizing effect the moon has on the orientation of earth's axis would not be in play. Life for us would be much more difficult or perhaps impossible, if Earth's tilt were unstable enough to make predictability of seasonal change, impossible instead of only difficult. Flora and fauna would have evolved quite differently, and our biodiversity would have a different look than what we see today. Many species that we now know, would simply not exist.
Venus and Mars, both virtually moonless, seem not to be troubled by unstable axes. Perhaps this is due to the relative fluidity of Venus and relative solidity of Mars. However, there are other environmental factors that might influence stability: speed of rotation, atmosphere, temperature, among others. These two planets share certain properties with Earth, but are very different in many respects.
Earth, and its life, have had to adapt to the presence of our moon and its tides, so of course, without its influences, we know that many things would be different. We may be a little fuzzy though, on the extent and severity of some of those differences.
I doubt that anybody knows why there are stars in the universe, but I'd say that it was to keep all the planets that support life warm.
sattellites of what? the earth has one satellite, the mon.
The moon was about 90% of full; it was full on the 15th. On the 12th, the sun-object angle was 144.3 degrees.